I'm wondering how these work. Obviously the actual dimmin will be done by the same means as the rear view mirror and the glass will go dark and greenish (I presume?) but where exactly is the light sensor? Does each mirror have it's own sensor somewhere or do they work off the same one in the rear view mirror itself? The reason for asking was that, when my new car arrives in December, I want to be able to quickly identify all of the options. As the car is leased it will be delivered to the office by an agent and I want to be able to quickly check all the options are present before the guy leaves so that if there's a problem I can get on the blower to the lease company straight away. Most options are easy enough to identify but I was puzzled about the mirrors. Someone on tyresmoke said the dimming ones have a black "edge" around the glass, is this true and is this the sensor? My current list of options and checks: 170 engine - straight exhausts (no other conclusive evidence so far) DVD Satnav Plus - duh! BOSE sound system - silver BOSE strip above front door speakers Light & rain sensor pack - sensors on RVM and mount, AUTO setting on light switch Interior lighting pack - two red LEDs in front overhead console 3-spoke wheel with audio controls - duh! Auto-dimming & folding door mirrors - mirror switch has extra position for folded?? Electric lumbar support - 4-way switch on side of seats Front centre armrest - duh! Luggage pack - net & socket in boot Reversible boot mat - duh! Non-smoking pack - lack of ashtray!